From 89df62c3ca1746177e5f1bae540b6b85c27aadcd Mon Sep 17 00:00:00 2001 From: Ian Rogers Date: Fri, 26 May 2023 11:33:51 -0700 Subject: tools api fs: Avoid large static PATH_MAX arrays Change struct fs to have a pointer to a dynamically allocated array rather than an array. This reduces the size of fs__entries from 24,768 bytes to 240 bytes. Read paths into a stack allocated array and strdup. Fix off-by-1 fscanf %s in fs__read_mounts caught by address sanitizer. Signed-off-by: Ian Rogers Link: https://lore.kernel.org/r/20230526183401.2326121-7-irogers@google.com Cc: K Prateek Nayak Cc: Ravi Bangoria Cc: Mark Rutland Cc: Ross Zwisler Cc: Steven Rostedt (Google) Cc: Sean Christopherson Cc: Yang Jihong Cc: Peter Zijlstra Cc: Adrian Hunter Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Masami Hiramatsu (Google) Cc: Namhyung Kim Cc: Leo Yan Cc: Andi Kleen Cc: Alexander Shishkin Cc: Kan Liang Cc: Tiezhu Yang Cc: Ingo Molnar Cc: Paolo Bonzini Cc: linux-kernel@vger.kernel.org Cc: linux-perf-users@vger.kernel.org Signed-off-by: Arnaldo Carvalho de Melo --- tools/lib/api/fs/fs.c | 25 ++++++++++++++++++------- 1 file changed, 18 insertions(+), 7 deletions(-) (limited to 'tools/lib/api/fs') diff --git a/tools/lib/api/fs/fs.c b/tools/lib/api/fs/fs.c index 82f53d81a7a7..22d34a0be8b4 100644 --- a/tools/lib/api/fs/fs.c +++ b/tools/lib/api/fs/fs.c @@ -88,7 +88,7 @@ static const char * const bpf_fs__known_mountpoints[] = { struct fs { const char *name; const char * const *mounts; - char path[PATH_MAX]; + char *path; bool found; bool checked; long magic; @@ -151,17 +151,23 @@ static bool fs__read_mounts(struct fs *fs) bool found = false; char type[100]; FILE *fp; + char path[PATH_MAX + 1]; fp = fopen("/proc/mounts", "r"); if (fp == NULL) - return NULL; + return false; while (!found && fscanf(fp, "%*s %" STR(PATH_MAX) "s %99s %*s %*d %*d\n", - fs->path, type) == 2) { + path, type) == 2) { - if (strcmp(type, fs->name) == 0) + if (strcmp(type, fs->name) == 0) { + free(fs->path); + fs->path = strdup(path); + if (!fs->path) + return false; found = true; + } } fclose(fp); @@ -188,8 +194,11 @@ static bool fs__check_mounts(struct fs *fs) ptr = fs->mounts; while (*ptr) { if (fs__valid_mount(*ptr, fs->magic) == 0) { + free(fs->path); + fs->path = strdup(*ptr); + if (!fs->path) + return false; fs->found = true; - strcpy(fs->path, *ptr); return true; } ptr++; @@ -227,10 +236,12 @@ static bool fs__env_override(struct fs *fs) if (!override_path) return false; + free(fs->path); + fs->path = strdup(override_path); + if (!fs->path) + return false; fs->found = true; fs->checked = true; - strncpy(fs->path, override_path, sizeof(fs->path) - 1); - fs->path[sizeof(fs->path) - 1] = '\0'; return true; } -- cgit From 20dcad8f03117e50df569d18f6709d68807fedb8 Mon Sep 17 00:00:00 2001 From: Ian Rogers Date: Fri, 26 May 2023 11:33:52 -0700 Subject: tools lib api fs tracing_path: Remove two unused MAX_PATH paths tracing_mnt was set but never written. tracing_events_path was set and read on errors paths, but its value is exactly tracing_path with a "/events" appended, so we can derive the value in the error paths. There appears to have been a missing "/" when tracing_events_path was initialized. Signed-off-by: Ian Rogers Link: https://lore.kernel.org/r/20230526183401.2326121-8-irogers@google.com Cc: K Prateek Nayak Cc: Ravi Bangoria Cc: Mark Rutland Cc: Ross Zwisler Cc: Steven Rostedt (Google) Cc: Sean Christopherson Cc: Yang Jihong Cc: Peter Zijlstra Cc: Adrian Hunter Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Masami Hiramatsu (Google) Cc: Namhyung Kim Cc: Leo Yan Cc: Andi Kleen Cc: Alexander Shishkin Cc: Kan Liang Cc: Tiezhu Yang Cc: Ingo Molnar Cc: Paolo Bonzini Cc: linux-kernel@vger.kernel.org Cc: linux-perf-users@vger.kernel.org Signed-off-by: Arnaldo Carvalho de Melo --- tools/lib/api/fs/tracing_path.c | 17 ++++++----------- 1 file changed, 6 insertions(+), 11 deletions(-) (limited to 'tools/lib/api/fs') diff --git a/tools/lib/api/fs/tracing_path.c b/tools/lib/api/fs/tracing_path.c index 7ba3e81274e8..30745f35d0d2 100644 --- a/tools/lib/api/fs/tracing_path.c +++ b/tools/lib/api/fs/tracing_path.c @@ -13,17 +13,12 @@ #include "tracing_path.h" -static char tracing_mnt[PATH_MAX] = "/sys/kernel/debug"; static char tracing_path[PATH_MAX] = "/sys/kernel/tracing"; -static char tracing_events_path[PATH_MAX] = "/sys/kernel/tracing/events"; static void __tracing_path_set(const char *tracing, const char *mountpoint) { - snprintf(tracing_mnt, sizeof(tracing_mnt), "%s", mountpoint); snprintf(tracing_path, sizeof(tracing_path), "%s/%s", mountpoint, tracing); - snprintf(tracing_events_path, sizeof(tracing_events_path), "%s/%s%s", - mountpoint, tracing, "events"); } static const char *tracing_path_tracefs_mount(void) @@ -149,15 +144,15 @@ int tracing_path__strerror_open_tp(int err, char *buf, size_t size, /* sdt markers */ if (!strncmp(filename, "sdt_", 4)) { snprintf(buf, size, - "Error:\tFile %s/%s not found.\n" + "Error:\tFile %s/events/%s not found.\n" "Hint:\tSDT event cannot be directly recorded on.\n" "\tPlease first use 'perf probe %s:%s' before recording it.\n", - tracing_events_path, filename, sys, name); + tracing_path, filename, sys, name); } else { snprintf(buf, size, - "Error:\tFile %s/%s not found.\n" + "Error:\tFile %s/events/%s not found.\n" "Hint:\tPerhaps this kernel misses some CONFIG_ setting to enable this feature?.\n", - tracing_events_path, filename); + tracing_path, filename); } break; } @@ -169,9 +164,9 @@ int tracing_path__strerror_open_tp(int err, char *buf, size_t size, break; case EACCES: { snprintf(buf, size, - "Error:\tNo permissions to read %s/%s\n" + "Error:\tNo permissions to read %s/events/%s\n" "Hint:\tTry 'sudo mount -o remount,mode=755 %s'\n", - tracing_events_path, filename, tracing_path_mount()); + tracing_path, filename, tracing_path_mount()); } break; default: -- cgit From 7a3fb8b5c4607b133a71d3f695d0f2653facec13 Mon Sep 17 00:00:00 2001 From: Ian Rogers Date: Fri, 26 May 2023 11:33:59 -0700 Subject: tools api fs: Dynamically allocate cgroupfs mount point cache, removing 4128 bytes from .bss Move the cgroupfs_cache_entry 4128 byte array out of .bss. Signed-off-by: Ian Rogers Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Andi Kleen Cc: Ingo Molnar Cc: Jiri Olsa Cc: K Prateek Nayak Cc: Kan Liang Cc: Leo Yan Cc: Mark Rutland Cc: Masami Hiramatsu Cc: Namhyung Kim Cc: Paolo Bonzini Cc: Peter Zijlstra Cc: Ravi Bangoria Cc: Ross Zwisler Cc: Sean Christopherson Cc: Steven Rostedt (VMware) Cc: Tiezhu Yang Cc: Yang Jihong Link: https://lore.kernel.org/r/20230526183401.2326121-15-irogers@google.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/lib/api/fs/cgroup.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-) (limited to 'tools/lib/api/fs') diff --git a/tools/lib/api/fs/cgroup.c b/tools/lib/api/fs/cgroup.c index 1573dae4259d..250629a09423 100644 --- a/tools/lib/api/fs/cgroup.c +++ b/tools/lib/api/fs/cgroup.c @@ -14,7 +14,7 @@ struct cgroupfs_cache_entry { }; /* just cache last used one */ -static struct cgroupfs_cache_entry cached; +static struct cgroupfs_cache_entry *cached; int cgroupfs_find_mountpoint(char *buf, size_t maxlen, const char *subsys) { @@ -24,9 +24,9 @@ int cgroupfs_find_mountpoint(char *buf, size_t maxlen, const char *subsys) char *p, *path; char mountpoint[PATH_MAX]; - if (!strcmp(cached.subsys, subsys)) { - if (strlen(cached.mountpoint) < maxlen) { - strcpy(buf, cached.mountpoint); + if (cached && !strcmp(cached->subsys, subsys)) { + if (strlen(cached->mountpoint) < maxlen) { + strcpy(buf, cached->mountpoint); return 0; } return -1; @@ -91,8 +91,13 @@ int cgroupfs_find_mountpoint(char *buf, size_t maxlen, const char *subsys) free(line); fclose(fp); - strncpy(cached.subsys, subsys, sizeof(cached.subsys) - 1); - strcpy(cached.mountpoint, mountpoint); + if (!cached) + cached = calloc(1, sizeof(*cached)); + + if (cached) { + strncpy(cached->subsys, subsys, sizeof(cached->subsys) - 1); + strcpy(cached->mountpoint, mountpoint); + } if (mountpoint[0] && strlen(mountpoint) < maxlen) { strcpy(buf, mountpoint); -- cgit From 97d5f2e9ee12cdc7214d5835d35c59404cfafee6 Mon Sep 17 00:00:00 2001 From: Ian Rogers Date: Fri, 9 Jun 2023 15:40:04 -0700 Subject: tools api fs: More thread safety for global filesystem variables Multiple threads, such as with "perf top", may race to initialize a file system path like hugetlbfs. The racy initialization of the path leads to at least memory leaks. To avoid this initialize each fs for reading the mount point path with pthread_once. Mounting the file system may also be racy, so introduce a mutex over the function. This does mean that the path is being accessed with and without a mutex, which is inherently racy but hopefully benign, especially as there are fewer callers to fs__mount. Remove the fs__entries by directly using global variables, this was done as no argument like the index can be passed to the init once routine. Issue found and tested with "perf top" and address sanitizer. Signed-off-by: Ian Rogers Cc: Adrian Hunter Cc: Jiri Olsa Cc: Namhyung Kim Cc: bpf@vger.kernel.org Link: https://lore.kernel.org/r/20230609224004.180988-1-irogers@google.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/lib/api/fs/fs.c | 211 ++++++++++++++++++++------------------------------ 1 file changed, 86 insertions(+), 125 deletions(-) (limited to 'tools/lib/api/fs') diff --git a/tools/lib/api/fs/fs.c b/tools/lib/api/fs/fs.c index 22d34a0be8b4..5cb0eeec2c8a 100644 --- a/tools/lib/api/fs/fs.c +++ b/tools/lib/api/fs/fs.c @@ -1,4 +1,5 @@ // SPDX-License-Identifier: GPL-2.0 +#include #include #include #include @@ -10,6 +11,7 @@ #include #include #include +#include #include #include @@ -43,7 +45,7 @@ #define BPF_FS_MAGIC 0xcafe4a11 #endif -static const char * const sysfs__fs_known_mountpoints[] = { +static const char * const sysfs__known_mountpoints[] = { "/sys", 0, }; @@ -86,69 +88,70 @@ static const char * const bpf_fs__known_mountpoints[] = { }; struct fs { - const char *name; - const char * const *mounts; + const char * const name; + const char * const * const mounts; char *path; - bool found; - bool checked; - long magic; -}; - -enum { - FS__SYSFS = 0, - FS__PROCFS = 1, - FS__DEBUGFS = 2, - FS__TRACEFS = 3, - FS__HUGETLBFS = 4, - FS__BPF_FS = 5, + pthread_mutex_t mount_mutex; + const long magic; }; #ifndef TRACEFS_MAGIC #define TRACEFS_MAGIC 0x74726163 #endif -static struct fs fs__entries[] = { - [FS__SYSFS] = { - .name = "sysfs", - .mounts = sysfs__fs_known_mountpoints, - .magic = SYSFS_MAGIC, - .checked = false, - }, - [FS__PROCFS] = { - .name = "proc", - .mounts = procfs__known_mountpoints, - .magic = PROC_SUPER_MAGIC, - .checked = false, - }, - [FS__DEBUGFS] = { - .name = "debugfs", - .mounts = debugfs__known_mountpoints, - .magic = DEBUGFS_MAGIC, - .checked = false, - }, - [FS__TRACEFS] = { - .name = "tracefs", - .mounts = tracefs__known_mountpoints, - .magic = TRACEFS_MAGIC, - .checked = false, - }, - [FS__HUGETLBFS] = { - .name = "hugetlbfs", - .mounts = hugetlbfs__known_mountpoints, - .magic = HUGETLBFS_MAGIC, - .checked = false, - }, - [FS__BPF_FS] = { - .name = "bpf", - .mounts = bpf_fs__known_mountpoints, - .magic = BPF_FS_MAGIC, - .checked = false, - }, -}; +static void fs__init_once(struct fs *fs); +static const char *fs__mountpoint(const struct fs *fs); +static const char *fs__mount(struct fs *fs); + +#define FS(lower_name, fs_name, upper_name) \ +static struct fs fs__##lower_name = { \ + .name = #fs_name, \ + .mounts = lower_name##__known_mountpoints, \ + .magic = upper_name##_MAGIC, \ + .mount_mutex = PTHREAD_MUTEX_INITIALIZER, \ +}; \ + \ +static void lower_name##_init_once(void) \ +{ \ + struct fs *fs = &fs__##lower_name; \ + \ + fs__init_once(fs); \ +} \ + \ +const char *lower_name##__mountpoint(void) \ +{ \ + static pthread_once_t init_once = PTHREAD_ONCE_INIT; \ + struct fs *fs = &fs__##lower_name; \ + \ + pthread_once(&init_once, lower_name##_init_once); \ + return fs__mountpoint(fs); \ +} \ + \ +const char *lower_name##__mount(void) \ +{ \ + const char *mountpoint = lower_name##__mountpoint(); \ + struct fs *fs = &fs__##lower_name; \ + \ + if (mountpoint) \ + return mountpoint; \ + \ + return fs__mount(fs); \ +} \ + \ +bool lower_name##__configured(void) \ +{ \ + return lower_name##__mountpoint() != NULL; \ +} + +FS(sysfs, sysfs, SYSFS); +FS(procfs, procfs, PROC_SUPER); +FS(debugfs, debugfs, DEBUGFS); +FS(tracefs, tracefs, TRACEFS); +FS(hugetlbfs, hugetlbfs, HUGETLBFS); +FS(bpf_fs, bpf, BPF_FS); static bool fs__read_mounts(struct fs *fs) { - bool found = false; char type[100]; FILE *fp; char path[PATH_MAX + 1]; @@ -157,22 +160,17 @@ static bool fs__read_mounts(struct fs *fs) if (fp == NULL) return false; - while (!found && - fscanf(fp, "%*s %" STR(PATH_MAX) "s %99s %*s %*d %*d\n", + while (fscanf(fp, "%*s %" STR(PATH_MAX) "s %99s %*s %*d %*d\n", path, type) == 2) { if (strcmp(type, fs->name) == 0) { - free(fs->path); fs->path = strdup(path); - if (!fs->path) - return false; - found = true; + fclose(fp); + return fs->path != NULL; } } - fclose(fp); - fs->checked = true; - return fs->found = found; + return false; } static int fs__valid_mount(const char *fs, long magic) @@ -194,11 +192,9 @@ static bool fs__check_mounts(struct fs *fs) ptr = fs->mounts; while (*ptr) { if (fs__valid_mount(*ptr, fs->magic) == 0) { - free(fs->path); fs->path = strdup(*ptr); if (!fs->path) return false; - fs->found = true; return true; } ptr++; @@ -236,45 +232,26 @@ static bool fs__env_override(struct fs *fs) if (!override_path) return false; - free(fs->path); fs->path = strdup(override_path); if (!fs->path) return false; - fs->found = true; - fs->checked = true; return true; } -static const char *fs__get_mountpoint(struct fs *fs) +static void fs__init_once(struct fs *fs) { - if (fs__env_override(fs)) - return fs->path; - - if (fs__check_mounts(fs)) - return fs->path; - - if (fs__read_mounts(fs)) - return fs->path; - - return NULL; + if (!fs__env_override(fs) && + !fs__check_mounts(fs) && + !fs__read_mounts(fs)) { + assert(!fs->path); + } else { + assert(fs->path); + } } -static const char *fs__mountpoint(int idx) +static const char *fs__mountpoint(const struct fs *fs) { - struct fs *fs = &fs__entries[idx]; - - if (fs->found) - return (const char *)fs->path; - - /* the mount point was already checked for the mount point - * but and did not exist, so return NULL to avoid scanning again. - * This makes the found and not found paths cost equivalent - * in case of multiple calls. - */ - if (fs->checked) - return NULL; - - return fs__get_mountpoint(fs); + return fs->path; } static const char *mount_overload(struct fs *fs) @@ -289,45 +266,29 @@ static const char *mount_overload(struct fs *fs) return getenv(upper_name) ?: *fs->mounts; } -static const char *fs__mount(int idx) +static const char *fs__mount(struct fs *fs) { - struct fs *fs = &fs__entries[idx]; const char *mountpoint; - if (fs__mountpoint(idx)) - return (const char *)fs->path; + pthread_mutex_lock(&fs->mount_mutex); - mountpoint = mount_overload(fs); + /* Check if path found inside the mutex to avoid races with other callers of mount. */ + mountpoint = fs__mountpoint(fs); + if (mountpoint) + goto out; - if (mount(NULL, mountpoint, fs->name, 0, NULL) < 0) - return NULL; - - return fs__check_mounts(fs) ? fs->path : NULL; -} + mountpoint = mount_overload(fs); -#define FS(name, idx) \ -const char *name##__mountpoint(void) \ -{ \ - return fs__mountpoint(idx); \ -} \ - \ -const char *name##__mount(void) \ -{ \ - return fs__mount(idx); \ -} \ - \ -bool name##__configured(void) \ -{ \ - return name##__mountpoint() != NULL; \ + if (mount(NULL, mountpoint, fs->name, 0, NULL) == 0 && + fs__valid_mount(mountpoint, fs->magic) == 0) { + fs->path = strdup(mountpoint); + mountpoint = fs->path; + } +out: + pthread_mutex_unlock(&fs->mount_mutex); + return mountpoint; } -FS(sysfs, FS__SYSFS); -FS(procfs, FS__PROCFS); -FS(debugfs, FS__DEBUGFS); -FS(tracefs, FS__TRACEFS); -FS(hugetlbfs, FS__HUGETLBFS); -FS(bpf_fs, FS__BPF_FS); - int filename__read_int(const char *filename, int *value) { char line[64]; -- cgit